Historical biogeography of the predominantly Australian plant family Goodeniaceae

AimThe plant family Goodeniaceae includes 12 genera, largely restricted to Australia. They are a diverse and conspicuous element of the country's ecosystems and an important clade to consider in the effort to reconstruct the historical biogeography of this continent. We used a time-calibrated molecular phylogeny to perform ancestral-area reconstructions for the family, in order to: (1) determine its area of origin; (2) test whether vicariance played a role in the history of lineages occupying the south-western and south-eastern regions; (3) trace diversification processes in the central arid zone; and (4) trace potential eastward dispersals into the Pacific. LocationAustralia and the Pacific. MethodsWe employed a previously published molecular dataset to develop a time-calibrated phylogeny for the Goodeniaceae using beast 1.6.1 with both primary and secondary node calibrations. Ancestral areas were reconstructed via both dispersal-extinction-cladogenesis (DEC) and statistical dispersal-vicariance analysis (S-DIVA). ResultsThe Goodeniaceae split from Asteraceae + Calyceraceae c. 78Ma, with the divergence of the Lechenaultia, Anthotium and Dampiera (LAD) clade from the remainder of the family c. 67Ma. Although the geographical origin of the family is equivocal, the LAD clade originated in south-western Australia, and the remainder of the family, especially Goodenia s.l., probably originated in the central Eremaean zone. The majority of Goodenia cladogenesis events occurred during the Miocene, with expansions to the north, south-east and south-west. The crown radiation of Scaevola s.l. occurred later, during the second half of the Miocene, and has involved several recent extra-Australian dispersals into the Pacific. Main conclusionsAlthough it is unclear where in Australia the family originated, our results support a south-western origin for the LAD clade and considerable diversification of some clades within Goodenia s.l. and Scaevola s.l. in that zone. A relative paucity of mid-Miocene sister relationships between south-western and south-eastern lineages suggests that the occupants of these regions were not affected by contemporary vicariance events. Instead, our results suggest that the aridifying Eremaean zone was an important source and sink for lineages, especially in Goodenia s.l. Dispersal is inferred for the extra-Australian lineages due to their recent origins.